Some prior art agricultural and/or industrial irrigation systems comprise an irrigation liquid supply conduit, connected to a plurality of drop lines, each having a diffuser device for uniformly distributing a liquid jet to an underlying soil portion to be irrigated.
A diffuser device typically comprises a main body with a tubular passage having one end connected to the drop line and the opposite end having a nozzle for delivery of a downward liquid jet.
Furthermore, the device comprises a deflector member for obstructing and radially deflecting the liquid jet that flows out of the tubular passageway, for uniform distribution thereof over the soil portion to be irrigated.
The deflector member generally comprises a stem, which is designed to be introduced into the tubular body and has one plate-like end before the nozzle for interacting with and diffusing the liquid jet delivered thereby.
The deflector member is typically removably coupled to the tubular body to allow rotation of the stem and the plate relative to a vertical axis, due to the pressure exerted by the jet.
VI2008A000175, in the name of the Applicant hereof, discloses a liquid diffuser device for irrigation systems as described hereinbefore which has means for supporting the stem with the bottom wall of the tubular body.
These means are equipped with an intermediate contact member integral with the lower end of the stem and adapted to continuously contact the bottom wall of the tubular body to prevent downward translation of the stem, caused by wear of the contact surfaces and to maintain the distance of the plate from the nozzle unchanged.
Furthermore, the bottom wall of the tubular body may have a first concave seat for accommodating a first sphere and the end bottom surface of the stem may have a second concave seat for receiving therein a second sphere defining the intermediate member.
The second sphere has a smaller diameter as compared with the first sphere, for rotation of the stem relative to the bottom wall and oscillation thereof relative to the vertical axis of the tubular body, resulting in nutation of the plate relative to said axis.
A first drawback of this arrangement is that its construction and assembly are rather complex and it has a relatively high cost.
This is because the second sphere must be manually inserted into the corresponding concave seat formed in the bottom surface of the stem, which is a time consuming operation, requiring remarkable manual dexterity of the assembly operator.
A further drawback of this known arrangement is that the provision of the intermediate member only partially reduces stem wear, and the resulting efficiency loss in the device.
Indeed, the nutation of the plate causes the side wall of the concave seat to wear, and may generate oscillatory vibrations of the plate, with the risk of causing the device to break or blocking the movement of the stem, which will prevent uniform distribution of the liquid jet on the soil portion to be irrigated.
Also, a further drawback of this solution is that, due to the wear of the seat, the diffuser member is required to be periodically replaced, which will increase the maintenance costs of the system.
Furthermore, during periodic maintenance of the diffuser device, the operation of the system is stopped, and the soil remains unirrigated for a given time, which will reduce the growth of crops or irremediably cause their destruction.